As a touch display apparatus becomes increasingly popular, people's requirement for quality of the touch display apparatus is higher and higher. Since in-cell touch technique has advantages of thin thickness and high touch sensitivity and so on, this technique has been widely applied.
The in-cell touch technique integrates touch elements inside a display panel so that the panel per se has a touch function, and thus an effect and application of touch can be achieved without additionally fitting and assembling with the touch panel. By taking a typical thin film transistor-liquid crystal display (TFT-LCD) as an example, its characteristic is the manufacturing technique of completing touch sensing elements in a TFT-LCD standard manufacturing process. Since it does not need to additionally set a touch panel, there is no problem of fitting and contraposition, so that weight and thickness are greatly reduced, and the product will be thinner. Due to the use of in-cell technique, a product of display apparatus does not need any frame so as to realize a full plane design, and the product has a simpler design and a broader application field.
The known in-cell touch technique generally adopts a projection multi-point capacitive touch mode, and the acquisition of touch signals is performed through two layers of signal lines, wherein one layer of signal lines are driving lines (Tx lines), and the other layer of signal lines are sensing lines (Rx lines). The two layers of lines are vertical to each other. In terms of implementations, a scanning mode is adopted to drive each driving line in turns and measure whether a capacitive coupling phenomenon occurs to a point of the sensing line interlaced with this driving line. Through scanning one by one, an exact touch point position can be obtained, and multi-touch can be realized.
For the known touch display apparatus, when pixels and scanning lines in the same row or column are charged simultaneously, they may interfere with each other, and thus the processes of pixel charging and scanning are always performed in a time division mode. In particular, there are generally two timing modes within a frame, i.e., V-Blank and H-Blank. The V-Blank mode means to reserve a period of time to perform touch signal scanning after all the pixels are charged within a frame, that is, pixel charging and touch scanning are performed separately. Such mode only supports a touch scanning refresh rate the same as a display picture refresh rate (1:1 relationship). If the picture refresh rate is 60 HZ, then the touch scanning refresh rate is only 60 HZ. In order to increase flexibility of the touch, the key is to increase the frequency of the touch scanning. In the pursuit of an experience effect of high-performance touch, a touch refresh rate of 120 HZ or greater is necessary.
The H-Blank mode can effectively increase the touch scanning refresh rate. This mode performs part of touch signal scanning by reserving a period of time in the interval of pixel charging in certain number of rows within a frame, that is, the pixel charging and the touch scanning are alternately performed. Such mode can support a touch scanning refresh rate being greater than the picture refresh rate, i.e., having a multiply relationship with the picture refresh rate.